Magnetic and structural studies of GdFe_2-xHf_x alloys

A series of GdFe_2-xHf_x alloys, where x=0, 0.1, 0.15, 0.2, and 0.3, have been prepared by arc-melting. X-ray diffraction (XRD) reveals that all the samples studied have the cubic Cu₂Mg type structure. The lattice parameter (a) and the unit cell volume (V) are found to increase with increasing Hf concentration. The magnetization were measured in a superconducting quantum interference device magnetometer (SQUID) in the temperature range 5-300K. All samples under investigation are magnetically ordered at room temperature and at 5K and the saturation magnetization is found to increase with increasing the Hf concentration at both temperatures. The increase in the saturation magnetization is due to the replacement of magnetic Fe by non-magnetic Hf which reduces the Fe sublattice moment in the GdFe _2-xHf_x ferromagnetic alloys. The Curie temperature (T _c) is determined using vibrating sample magnetometer (VSM) for all samples and found to decrease linearly with increasing Hf concentration, from 800K for x=0-590K for x=0.3.